Firing mechanism for reversible automatic cannon

ABSTRACT

IN AN AUTOMATIC CANNON COMPRISING A CHAMBERED DRUM DRIVEN IN EITHER DIRECTION THROUGH A GENEVA MOVEMENT FOR SUCCESSIVELY INDEXING THE CHAMBERS AT FEEDING AND FIRING POSITIONS, SUCH GENEVA MOVEMENT INCLUDING A CONTINUOUSLY ROTATED CRANK WHEEL AND AN INTERMITTENTLY ROTATED STARWHEEL CONNECTED TO THE DRUM, A FIRING MECHANISM INCLUDES A FIRING PIN NORMALLY BIASED FROM A RETRACTED TO A STRIKING POSITION AND MOUNTING A SEAR NORMALLY BIASED THEREON FROM A RETRACTED TO A LATCHING POSITION FOR RELEASABLY HOLDING THE FIRING PIN COCKED. A TRIGGER ASSEMBLY INCLUDES A SLEEVE TELESCOPICALLY MOUNTED TO THE FIRING PIN AND A CAM LOBE CONTACTABLE BY THE CAM LOBE ON THE CRANK WHEEL FOR CONVERTING ROTATION THEREOF TO TRANSLATIONAL DISPLACEMENT OF THE SLEEVE FOR COMPRESSING THE FIRING PIN SPRING AND ACTING AGAINST THE SEAR FOR DISPLACEMENT THEREOF TO RELEASE THE FIRING PIN WHEN ROTATION OF THE DRUM IS STOPPED TO INDEX EACH OF THE CHAMBERS THEREIN AT THE FIRING STATION. THE CAM LOBES ON THE CRANK WHEEL AND IN THE TRIGGER ASSEMBLY ARE SYMMETRICALLY DESIGNED TO PERMIT SMOOTH CAMMING CONTACT THEREBETWEEN WHEN THE DRUM IS DRIVEN IN EITHER DIRECTION.

Nov. 16, 1971 H. H. WIESE 3,620,124

FIRING MECHANISM FOR REVERSIULF AUTOMATTC CANNON Filed Jan. ,12, 1970 (3 .jhmsLu-Jilnml, 1

INVENTOR H111 015 H .Wiese ATTORNEYS Nov. 16, 1971 H. H. WIESE 3,620,124

Filed Jan. 12, 1970 6 ShcetsSh0et NNNNNN OR M W ATTOFQINEYS a! H. H. WIESE 3,620,124

FIRING MECHANISM FOR REVERSIBLE AUTOMATIC CANNON Nov. 16, 1971 Filed Jan. 12, 1970 w 5 RE Y 0.1 .E NW. N WE w Ld A m m a Hm M: v. M

nu l Nov. 16, 1971 H. H. WIESE 3,620,124

FIRING MECHANISM FOR REVERSIBLH AUTOMATIC UANNUN Filed Jan. 12, 1970 G FilmuLn-iillunl, B

I NVENTOR HurulflHWiesa .3 BY ,W W

Nov. 16, 1971 H. H. WIESE 3,620,124

FIRING MECHANISM FOR REVERSlDLXrX AUTOMATIC UANNUN Filed Jan. 12, 1970 (3 .HumLu-filmut. I?

INVENTOR Humid HJNiese RNEYS United States Patent Ofice 3,620,124 Patented Nov. 16, 1971 U.S. CI. 89-13 R 7 Claims ABSTRACT OF THE DISCLOSURE In an automatic cannon comprising a chambered drum driven in either direction through a Geneva movement for successively indexing the chambers at feeding and firing positions, such Geneva movement including a continuously rotated crank wheel and an intermittently rotated star wheel connected to the drum, a firing mechanism includes a firing pin normally biased from a retracted to a striking position and mounting a scar normally biased thereon from a retracted to a latching position for releasably holding the firing pin cocked. A trigger assembly includes a sleeve telescopically mounted to the firing pin and a cam lobe contactable by the cam lobe on the crank wheel for converting rotation thereof to translational displacement of the sleeve for compressing the firing pin spring and acting against the sear for displacement thereof to release the firing pin when rotation of the drum is stopped to index each of the chambers therein at the firing station. The cam lobes on the crank wheel and in the trigger assembly are symmetrically designed to permit smooth camming contact therebetween when the drum is driven in either direction.

The invention described herein may be manufactured, used, and licensed by or for the Government for governmental purposes without the payment to me of any royalty thereon.

BACKGROUND OF THE INVENTION This invention relates to automatic cannons, especially those for firing caseless rounds, and pertains more particularly to the firing mechanisms thereof.

A particular automatic cannon includes a four-chamber drum which is selectively driven in opposite directions by a reversible electric motor. A Geneva movement is operationally disposed between the motor and drum to provide intermittent rotation thereof for successively rotating each of the chambers to four stations including a firing station, an ejection station, and two loading stations oppositely disposed therebetween, and pausing momentarily at each for loading and firing functions. A magazine is mounted at each loading station for registry with the chambers when respectively indexed thereat, and solenoid actuated gates control the passage of the rounds from the magazines to the chambers. An electrical system includes a microswitch actuated by the Geneva movement to control the operation of the gates so as to feed the rounds from one magazine to the indexed one of the chambers when the drum is rotated in one direction and from the other magazine to the indexed chamber when the drum is rotated in the opposite direction.

SUMMARY OF THE INVENTION Because of the reversibility of such a cannon, a firing pin mechanism must be provided which is operable in whichever direction the drum is rotated. It is therefore a principal object of this invention to provide a firing pin mechanism including a cam lobe on a rotating member actuatable against a cooperative cam lobe relative to a sleeve for compressing the firing pin spring and which, when near the end of its compression stroke, trips the sear permitting the firing pin to accelerate forward to discharge the firing position round with the cam lobes being symmetrically designed so as to be effective in displacement of the sleeve in whichever direction the rotating member is rotated.

It is a further object of this invention to mount the actuating cam lobe to the Geneva movement which controls the rotation of the drum to the different stations so as to time the firing of the rounds to the actuation of the drum.

Further objects and advantages of the invention will be apparent from the following specification and the accompanying drawings which are for the purpose of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary, longitudinally cross-sectioned view of the cannon showing the firing pin in the firing position;

FIG. 2 is a cross-sectional view taken along line 22 of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 33 of FIG. 1;

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1;

FIG. 5 is a cross-sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is an enlarged fragmentary cross-sectional view taken along line 5-5 of FIG. 4;

FIG. 7 is a view similar to FIG. 6 but showing the firing pin actuated to its retracted position;

FIG. 8 is a view similar to FIGS. 6 and 7 but showing the sear partially actuated from its firing pin holding position;

FIG. 9 is a cross-sectional view taken along line 9-9 of FIG. 7;

FIG. 10 is a cross-sectional view taken along line 10-10 of FIG. 5; and

FIG. 11 is a cross-sectional view taken along line 11-11 of FIG. 10.

DESCRIPTION OF THE PREFERRED EMBODIMENT Shown in the figures is an automatic cannon 12 such as is disclosed in my copending application for Feeding Mechanism of an Automatic Cannon for Firing Caseless Ammunition, Ser. No. 864,849, filed Oct. 8, 1969. Cannon 12 is adapted for firing rounds 14, each of which is provided with a primer 15 centrally located at the rear end thereof, and comprises a housing 16 which encloses a drive unit 18 and a chambered drum 20 driven thereby through at Geneva movement 22. A feeding mechanism 24 controlled by Geneva movement 22 through an electrical circuit (not shown) controls the passage of rounds 14 to the drum; and firing mechanism 26 discharges the rounds in drum 20 when aligned with barrel 28.

Drive unit 18 comprises a reversible electrical motor 36 which is rotatable at variable speeds in opposite directions and is connected mechanically to a gear reduction unit 38. Such gear reduction unit 38 is provided with an output shaft 40 which extends forwardly from case 42 for the gear reduction unit in axial alignment with the bore of barrel 28. Mounted on the extending portion of shaft 40, so as to be rotated thereby, is a crank wheel 44 which is a part of Geneva movement 22. As shown in FIGS. 2

and 3, a pair of crankpins 46 are mounted to crank wheel 44 so as to be diametrically disposed thereon and equally spaced from the axis thereof. Axially mounted on the front face of crank wheel 44 and fixed thereto between crankpins 46 is a locking wheel 48 which includes a pair of similar, diametrically opposed convex sections 50 and a pair of concave sections 52 having the same radius as the convex sections and symmetrically located therebetween. Geneva movement 22 also includes a star wheel 54 which is mounted on the rearwardly extending section of axle 56 which rotatingly mounts drum 20 in housing 16. As especially shown in FIG. 2, star wheel 54 is provided with four symmetrically spaced radial channels 58 each being arranged to receive one of the crankpins 46 during rotation of crank wheel 44 to transfer rotation thereof to the star wheel, and symmetrically formed between pairs of the channels are four arcuate recesses 60. Such recesses 60 are arranged to matingly receive one of the convex sections 50 when both crankpins are free of all channels 58. Thus, when one of the convex sections 50 is received by one of the recesses 60, star wheel 54 is held thereby against rotation. As crank wheel 44 continues to turn relative to star wheel 54, one of the crankpins 46 enters the one of the channels 58 aligned therewith and the locking one of the convex sections 50 is moved out of the cooperating one of the recesses 60 so that the continued rotation of the crank wheel moves such crankpin against the side of the engaged channel to transfer rotation of the crank wheel to the star wheel. Star wheel 54 is rotated thereby 90 which aligns the opposite one of the crankpins 46 with the next one of the channels 58 and the opposite convex section 50 into the next recesses 60 so that drum 20 is rotated in sequential periods of rotation and non-rotation.

Drum 20 is provided with four symmetrically arranged chambers 62 which are respectively designed to receive round 14 from the front end of the drum. Through the operation of Geneva movement 22, drum 20 is rotated so that each of the chambers 62 is rotated to four stations during one revolution of the drum and is momentarily held stationary at each of the stations when located thereat. Such stations comprise a firing station located at the 12 oclock position in alignment with barrel 28, an ejection station located opposite thereof at the six oclock position; and two loading stations located oppositely therebetween.

Mounted to the front face of case 42 is a microswitch 64 having a roller which has rolling contact with stepped circumference 66 of crank wheel 44. Microswitch 64 is connected electrically to solenoids (not shown) which actuate gates (not shown) that respectively control the passage of rounds 14 from a supply source into drum 20, as fully described in my previously referenced application. Circumference 66 is designed for cooperation with microswitch 64 so that during that portion of the rotation of crank wheel 44 when drum 20 is rotated the gates are closed and when the drum is stationary the gates are open for feeding purposes. Also, while drum 20 is stationary, firing mechanism 26 is arranged, as hereinafter described to fire round 14 indexed at the firing position.

Firing mechanism 26 includes a firing pin assembly 68 and a pair of symmetrically formed cam lobes 70 on the front face of locking wheel 48 so as to be diametrically and symmetrically disposed respective to the axis thereof and so as to extend forwardly therefrom, as shown in FIG. 3. Firing pin assembly 68 is mounted through a bore 71 which extends longitudinally through a breech plate 72 located in housing 16, normal to the longitudinal axis thereof, immediately rearward of drum 20.

Firing pin assembly 68 comprises a supporting anvil 74 which is threadingly mounted in bore 71. Anvil 74 is provided with a longitudinal bore 76 which slidingly mounts a cylindrical firing pin 78 for longitudinal displacement between a forward striking position, as shown in FIGS. and 6, and a rearward retracted position, as

shown in FIG. 7. Firing pin 78 is provided with a head *80 the rear side of which is beveled at 82. The largest diameter of head 80 is larger than that of the remaining body portion of firing pin 78. A striking pin 84 is received by a mating hole 85 which extends centrally into head 80 from the front face thereof so that a portion of the striking pin extends forwardly therefrom in position to strike primer 15 of round 14 when firing pin 78 is accelerated to the striking position. The front end of bore 76 is counterborcd at 86 from the front end thereof sufficiently to permit setback of head 80 thereinto when firing pin 78 is in its retracted position. The rear end of counterbore 86 is countersunk at 88 to form a tapered surface 90 having the same inclination relative to the longitudinal axis of firing pin 78 as beveled surface 82 so that when the firing pin is in its retracted position such beveled and tapered surfaces are in pressed contact to form a gas tight seal which prevents passage of discharge gas into bore 76 when round 14 is fired. Rings 92 are seated in suitable annular recesses 94 around firing pin 78 rearward of head 80 to provide further seals against passage of discharge gas along bore 76.

A channel 96 extends along the upper portion of firing pin 78 from the rear end thereof to a bottomed well 98 extending radially inward from the outside of the firing pin to receive a scar 100. A pin 102 extends laterally through mating hole 104 through the rear end of scar and holes 106 on opposite sides of channel 96 to mount the sear to the firing pin for pivotal displacement relative thereto between a latching position, shown in FIG. 7, wherein front end 108 projects above the channel, and a retracted position, shown in FIG. 6, wherein the front end is nested therein. A coiled spring 110 is seated in well 98 so as to act against sear 100 to normally bias it to its latching position.

Sear 100 is mechanically actuated to its retracted position by a trigger assembly 116- which includes a sleeve 118 of cylindrical configuration. Sleeve 118 is provided with a threaded portion 120 and a bearing portion 121 of larger diameter which extends forwardly therefrom and which is slidingly received by a counterbore 122 that extends forwardly into anvil 74 from the rear end thereof to an annular shoulder 124. A stepped bore 125 extends outwardly into sleeve 118 from the front end thereof and includes a front section 127 which slidingly receives the rear end of firing pin 78 for telescopic displacement relative to the sleeve, and a rear section 126 of smaller diameter which extends from such front section to a bottom 128. A spring 130 is operationally disposed between bottom 128 and the rear end of firing pin 78 to bias the firing pin forwardly relative to sleeve 118. Longitudinally elongated slots 132 are provided in sleeve 118 to slidingly receive extending ends 134 of pin 102 to prevent relative rotation of the sleeve and firing pin 78 while permitting relative translational displacement. Front end 108 of sear 100, when in the latching position, extends into the space between firing pin 78 and counterbore 122 so as to be contactable with shoulder 124, as shown in FIG. 8, for releasably holding the firing pin in cocked position against the bias of spring 130. When sleeve 118 is displaced forwardly relative to firing pin 78, as shown in FIG. 8, front end 136 of the sleeve cammingly contacts inclined side 138 of scar 100 to displace it against the bias of spring 110 to its retracted position free of shoulder 124. Extending downwardly from firing pin 78 is a stop 140 which is contactable with shoulder 124 to prevent forward displacement of the firing pin beyond its striking position.

Threadingly mounted to threaded portion 120 of sleeve 118, so as to be carried thereby, is a cam plate assembly 142 which comprises a mounting plate 144 and a cam plate 146. Mounting plate 144 is threadingly mounted to sleeve 118 and cam plate 146 is mounted to the mounting plate by tongue and groove means 148 for sliding vertical displacement between an engaging position, as shown in FIG. 5, and a disengaged position, as shown in FIG. ll.

A vertically elongated slot 150 in cam plate 146 permits the extension of sleeve 118 therethrough and vertical displacement of the cam plate relative thereto. Cam plate 146 is biased to the engaging position by a pair of springs 152 and is releasably held therein by detent means 154.

Provided on the rear face of cam plate 146, immediately above slot 150, is a cam lobe 158 which extends rearwardly from the cam plate so as to be sequentially contacted by cam lobes 70 on locking wheel 48 during rotation thereof. Cam lobe 158 is symmetrically formed, as are also cam lobes 70, so that smooth camming contact is made between the cam lobes whichever direction locking wheel 48 is rotated, to displace cam plate assembly 142 longitudinally responsive to the rotation of crank wheel 44. A coiled compression spring 160 is operationally disposed between mounting plate 144 and a shoulder 161 formed by a counterbore 162 of bore 71 for biasing sleeve 118, through cam plate assembly 142, to its retracted position. Cam lobe 158 and cam lobes 70 are so designed that when contact is made therebetween, during rotation of locking wheel 48, sleeve 118 is displaced forwardly with front end 136 thereof making camming contact with inclined side 13-8 of scar 100 to actuate the sear to its retracted position free of shoulder 124. Cam lobe 158 and cam lobes 70 are also so designed that the apexes of those in contact pass each other when one of the convex sections 50 is centrally located in one of the recesses 60, as shown in FIG. 2.

Firing mechanism 26 also includes a manually actuated safety device 163 for rendering cannon l2 inoperative. Referring to FIGS. 5, and 11, safety device 163 includes an arm 164 which extends integrally forward from the top side of cam plate 146 and a crankshaft 166 which extends laterally through housing 16. Crankshaft 166 includes a crankpin 168 which is rotatable against the underside of arm 164 to convert rotation of the crankshaft to translational upward displacement of cam plate 146. The throw of crankpin 168 is sufiicient to move cam plate 146 from the engaging position, shown in FIG. 5, to the disengaged position, shown in FIG. 11, wherein cam lobe 158 thereon is located away from any possible contact with cam lobes 70. Crankshaft 166 is rotated by means of a handle 170 through beveled gears 172, as shown in FIG. 10.

OPERATION When motor 36 is energized to fire cannon l2, crank wheel 44 of Geneva movement 22 is rotated to bring crankpins 46 thereon alternately into engagement with successive ones of the channels 58 to rotate drum 20 90 at each engagement. This indexes chambers 62 in drum 20 successively at the four stations whereby during each period of rotation of the drum one of the chambers is rotated from the applicable one of the two feeding stations to the firing station. When drum 20 is indexed to locate the four chambers 62 at their respective stations, one of the two convex sections 50 on locking Wheel 48 enters the aligned recess 60 to secure the drum against rotation until such convex section exits from the engaged recess.

As convex section 50 enters the aligned recess 60, one of the cam lobes 70 approaches contact with cam lobe 158 so that when the convex section is centrally located in the recess, the apexes of such two cam lobes are in contact. During the engagement between cam lobe 158 and the respective cam lobe 70, trigger assembly 116 is displaced forwardly to compress sleeve 118 and move front end 136 along inclined side 138 of sear 100 which is thereby pivoted free of shoulder 124 to release firing pin 78 for forward acceleration by spring 130 to fire round 14 in the indexed chamber 62. Under the influence of the discharge gas which acts upon head 80 of firing pin 78 the firing pin is displaced rearwardly against the bias of spring 130, with the ends of pin 102 moving along slots 132, to where bevel surface 82 on the head makes sealing contact with tapered surface in bore 76 to prevent passage of the discharge gas along such bore. As the engaging cam lobe 70 moves olf cam lobe 158 by continued rotation of crank wheel 44, trigger assembly 116 is permitted to return to its normal forward position, through the bias of spring 160, and sear snaps into its latching position when front end 108 thereof is located rearwardly of shoulder 124. Firing mechanism 26 is now ready for the next firing cycle.

I wish it to be understood that I do not desire to be limited to the exact details of the embodiment of the invention as described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. In an automatic cannon provided with a rotary member, a firing mechanism comprising a firing pin, a spring disposed responsive to compression thereof for accelerating said firing pin to a striking position, a scar pivotally mounted on said firing pin and arranged for releasably holding said firing pin in a cocked position against the bias of said spring, a sleeve disposed for relative displacement on said firing pin and for operational cooperation with said spring and said sear for compressing said spring and actuating said sear to release said firing pin responsive to relative movement respective thereto, cam means for converting rotation of said rotary member in either direction to relative displacement of said sleeve respective to said firing pin, said cam means comprising a first cam lobe of symmetrical configuration on said rotary member, and a second cam lobe of symmetrical configuration disposed relative to said sleeve and for sequential contact by said first cam lobe responsive to rotation of said rotary member.

2. The invention as defined in claim 1 and including means for displacing said second cam lobe away from contact by said first cam lobe to prevent operation of the cannon.

3. The invention as defined in claim 2 wherein said means for displacing said second cam lobe includes a mounting plate fixedly mounted to said sleeve, a cam plate comprising said second cam lobe slidingly mounted to said mounting plate by tongue and groove means for translational displacement between a position wherein said second cam lobe is contactable by said first cam lobe and a position wherein said second cam lobe is located away from contact by said first cam lobe, actuating means for displacing said cam plate between said two positions, and handle means exterior of said cannon for operating said actuating means.

4. The invention as defined in claim 3 wherein said actuating means comprises an arm extending from said cam plate, a crankshaft including a crankpin actuatable against said arm responsive to rotation of said crankshaft to displace said cam plate to the position wherein said second cam lobe is located away from contact by said first cam lobe, and including gear means operationally disposed between said crankshaft and said handle for transferring rotation thereof to said crankshaft.

5. The invention as defined in claim 4 wherein said firing mechanism includes an anvil having a bore for slidingly mounting said firing pin and a countersunk section of said bore forming a tapered surface, and wherein said firing pin comprises a head, and a beveled surface formed on said head contactable with said tapered surface responsive to discharge of a round by said firing pin to form a gas seal preventing passage of discharge gas along said bore.

6. The invention as defined in claim 4 wherein said cannon also includes a driving means, a drum comprising a plurality of chambers each adapted for receiving a round and holding the round for discharge, and means including said rotary member for transferring rotation of said driving means to said drum in sequential periods of rotation to locate each of said chambers at stations for round feeding and firing functions and secure said drum against rotation during performance of such functions.

7. The invention as defined in claim 6 wherein said last stated means comprises a Geneva movement including a crank wheel driven by said driving means and a star wheel connected to said drum and disposed for operation cooperation with said crank wheel for converting continuous rotation thereof to intermittent rotation of said drum to successively index said chambers therein at a feeding and a firing station, and wherein said rotary member is mounted to said crank wheel and is arranged thereon for cooperation with said second cam lobe when said chambers are being moved to the firing station to actuate said sleeve for compression of said firing pin spring and displacement of said sear for release of said firing pin.

References Cited UNITED STATES PATENTS 7/1938 Wildes et al 89-27 X 7/1948 Davis et al. 89-27 U.S. Cl. X.R. 

